Stent-grafts are used in body lumens and in particular, in vascular lumens. These grafts allow the use of the lumen in situations where the lumen may have a defect, such as a stenosis or an aneurysm. Stents perform functions that make them useful in combination with grafts. External stents are used to pull grafts open while avoiding the use of metallic materials on the inside of a graft, where the metals would be in contact with body fluids, such as blood. External stents thus avoid placement where they would be in contact with the body fluid. External stents, outside the graft, also avoid interference with the flow of the body fluid and are not an obstacle to passage of other medical devices though the inside of the graft. Internal stents are used to push the grafts open and to help seal the graft against the vessel wall. A stent, such as a zigzag stent, also may be used to anchor a graft in place, provided there are anchors or barbs on the stent for securing the stent, and hence the graft, in the desired location.
Previous grafts have included stents, but sometimes have defects that hinder their use. For example, FIG. 2 of U.S. Pat. No. 6,004,347 depicts a stent that may be difficult to manufacture because of the many resistance welds. A more serious difficulty is the method used to attach the stent to the graft. In order to properly secure the stent to the graft, according to the patent, eight penetrations or holes are needed for four successive stitches. Each stitch is positioned further away from a bend in the proximal end of the stent. This method spreads out the stress on the graft from the stent, but requires many penetrations per bend of the stent.
FIGS. 17-18 of U.S. Pat. No. 6,287,330 and FIGS. 19-21 of U.S. Pat. No. 6,221,102 depict stents used to secure a graft material. In these examples, the stent is separate from an attachment system that anchors the graft to the body lumen. Many stitches are required to secure the stent and the attachment system to the graft.